The invention concerns a sewing machine for large-surface, frame-clamped material held in place during sewing in a sewing-machine structure, the sewing head together with the gripper box being displaceable both transversely and longitudinally, and comprising frame-exchanging equipment.
Sewing machines for large-surface, frame-clamped material, for instance quilts, and comprising frame-exchanging equipment, are known for instance from U.S. Pat. Nos. 3,180,293; 3,382,835 and from the German patent 1,131,496. Such known machinery always entails unusually high expenditures for the frame-exchanging equipment mainly because complex lifting and shifting apparatus are provided not only at the sewing structure proper, but also at a preceding loading bench, said apparatus serving to raise the exchange frames together with the material to different heights, whereupon the exchange frames are shifted individually and the exchange is carried out. As regards the machines of the above documents, moreover, costs also are very large because the frame together with the material is displaced during sewing in the sewing machine proper in the longitudinal and transverse directions according to the pattern. Operators must constantly be present to monitor frame-exchange.